Nortel Network Wu Wei
The third generation of mobile communications (3G) is the hottest topic in today's telecommunications, and the relevant discussion has been very enthusiastic. Among them, the wireless access network occupies a lot of space. The new competitive landscape and the emergence of new wireless data services will have huge pressure and new challenges to the network. Operators urgently need to build a powerful heart for mobile communication network --- the future group core network.
Development direction of core network
With the expansion of IP business and the development of broadband technology, the future unified network of three-nuntel has become a big trend of the development of the entire telecommunications network. With the increasing footsteps of 3G, the broad prospect of mobile Internet is becoming a reality. As part of the telecommunications network, the wireless core network will also be evolved from the line switching network to the packet. New operators face new challenges: On the one hand, we must minimize the construction and operational costs of voice services to deal with increasingly fierce market competition. On the other hand, it is necessary to develop mobile data services to occupy market opportunities. Unlike fixed internets, mobile Internet will provide users with value-added services to create profits for operators, which requires a telecommunications data network. Specifically to the core network, the operator must be clear:
What technology uses the core technology of the next generation network?
How to develop the most appropriate evolutionary strategy?
How to ensure that the operator has the greatest benefit in an evolving core network?
The core business of the first generation and the second generation of wireless network is voice service. The corresponding core network is a line-exchanged network, that is, TDM line carries most of the speech and data services. With the increasing network capacity demand, the high cost of TDM technology, the complexity of the equipment, and the incorrect flexibility of management are increasing, and the TDM network cannot meet the requirements of high-speed packet-based voice, data, and multimedia services. The 2.5G representative represented by GPRS allows mobile operators to provide wireless data applications, but current implementation methods is to increase a parallel packet network from existing line-based networks, two network technologies , Business separation, respective operations and network management systems are also discrete, and operators have to support two networks, resulting in a series of issues such as high operation and maintenance cost and low network efficiency. Obviously, the discrete line exchange voice network and packet exchange data network is only the right to terminate.
With the rapid growth of the IP business and the development of grouping technology, the industry has basically reached a consensus on the next generation network: a support for multiple business voice, data, multimedia, supporting various mobile access technology IP Group core network. The current key is from the existing network of operators to design a simple, economic, and minimum risk, the core of the road.
In order to protect operators' investment, smooth evolutionary thinking is also fully embodied in the standard development process of 3G core network. International Standardization 3GPP first introduced the standard R99 of the third-generation mobile communication core network based on existing network in March 2000, and further improved in 2001. It is characterized by basic inheriting two domains of GPRS line exchange CS and packet swap PS, but further strengthening the function, identifying the requirements of service quality QOS QOS on various services. On the other hand, considering the development of integrated network, especially the rapid development of IP technology and optical communication technology and continuous improvement, 3G standardized organizations simultaneously open the Horsepower formation end-to-end full IP network standard. Since the difficulty of IP is implemented in the wireless access network, such as header compression, 3GPP takes two steps of steps, divides the original R00 full IP standard into two versions of R4 and R5. The R4 released in March this year pays attention to the packetization of the CS domain and the discreteization of NEs, the purpose is to facilitate the independent evolution and simplification of the network, improve efficiency, and enhance scalability. R5's standard formulation work is also tightening, but only a framework of future IP networks is present, and many details are still clear. The 3GPP has already proposed the concept of mobile IP in 2000. Its core is that all user terminals are online Internet access, which realizes always online, which depends on IPv6's wide application to provide sufficient IP address. The current IP technology has proposed a lot of methods in service quality OS, service level COS / flow control, such as DiffServ and RSVP, but must meet the full quality requirements of the 3G business terminal, but also need to be unified, mutual Make a lot of work in terms of interoperability. More important is to carry out the scale of the current network scale to accumulate engineering experience. It takes a few years to achieve large-scale practical applications. Operator's choice
The 3G standard clarifies the direction of integrated core network. Operators also hopes that their networks can carry speech, IP business, frame relays, multimedia and other services without need to build a network for each business. In reality, 3G mobile operators face more complicated situations, many operators have put in huge funds for 2G networks, and their return on investment needs a longer cycle, and the huge amount of 3G licenses have faced mobile operators. Unprecedented funds. Solution is not external: open source and throttle. Open source is actively developing, launching new mobile data services, mainly mobile Internet services for profit growth points and attracting more users, where operators need a flexible multi-service network, in order to achieve high-yield, network must meet telecommunications The requirements of the grade operation are to ensure that the end-to-end service quality provides different service levels to implement data traffic bills. The throttling is to make full use of technological advances, establish a concise and efficient integrated network with group exchange technology, saving investment, reducing operation and maintenance costs. Today, voice is still the main business and income source, and the wireless data service has just started, and its operational model also takes a period of exploration. This gradual progress of wireless business requires operators to choose a suitable network evolutionary strategy, and must ensure the correctness of the evolution direction, but also to ensure that the reality from speech has continued to grow steadily, but also launch data business in time, according to The situation of business development is reasonable to control network structure, network scale and network evolution rhythm, and achieve specific technical solutions based on demand rationally, in order to eventually meet the expectations of operators on sustained profitability.
Movies operators, such as British Telecom, German Telecom, Japan Docomo, Vodafone, etc. After weighing the loss of many pros and cons, there is almost no exceptionally to build a unified, group-based multi-service network. In the transport layer, the ATM technology network is selected, and the existing 2G voice service, GPRS IP service, and 3G multimedia services are all delivered on the ATM packet. One of the main considerations of operators is that the core network must meet the QoS requirements of a new generation of wireless services. Currently, IP technology has difficulties in handling real-time business, such as VoIP and other real-time IP services, the Quality Assurance system of IP services is not perfect and unified, and ATM-based solutions are quite mature, and they can provide flexible and reliable in multi-business environments. QoS, for example, operators can map the quality requirements of the IP application to the VC's protocol parameters, with the wireless resource management of the access network to implement the full QoS guarantee. This solution has extensive applications and has gained rich experience.
First, help operators save transmission costs and avoid the expansion of traditional TDM networks due to rapid expansion of user capacity. In addition, ATM-based voice packet gateways have many advantages, such as speech compression, mute detection, etc., can greatly improve the utilization of bandwidth, based on packet-based exchange, will eliminate dependence on line relay exchange layer and E1 transmission line , Reduce the complexity of network devices. At the same time, operators are required to flexibly control the network structure and scale, and distributed packet networks continue to grow as business increases. With the introduction of SGSN and GGSNs facing wireless data services, the same packet service platform will support wireless data services, which effectively protects investment, and the integration of data and speech makes this group network to play in the network evolution. The unified core network will fully demonstrate its role in the 3G wireless access network to gradually introduce the surgery in the 3G wireless access network. Bring the competitive advantage. In short, operators need a multi-service network platform that grows based on prior art, can grow with needs and business. It is worth emphasizing that 2.5G packet network development is crucial, but its significance is not only to start supporting high-speed data services, but more importantly, it helps operators how to handle different business types in their own networks. Voice, data, etc., and have obtained technical experience and business experience. These technical experiences include how to consider the use of reasonable packet core network network technology, how to make full utilization of existing network resources and further optimize the network structure, how to provide QoS, and attempts to fuse speech and data business. In terms of operation, operators will explore the generation and management of wireless data services, how to effectively manage network resources, how to bill fees. In short, operators now implement network integration to get valuable grouping multi-business business experience, than those operators who are waiting for mature final IP solutions for a certain period of time.
When the network evolves to 3G, 3G base stations and RNCs have been gradually deployed in the wireless access network, and the 3G core network evolved to the IP core network. The basic concept is to access signals of various standards and access methods to IP gateways. For any standard, this access signal is only three categories: business data, signaling, network management data, uses IP packets, and transmits them to its destination: business data to the communication other party; signaling To signaling processor; network management data is sent to the network management server.
Further evolution of the core network and MPLS
The first phase of the UMTS core network allows the operator to provide some primary 3G services to users. Operators can deploy wireless access gateways that match 3GPP wirelessAccess Gateway. Operators original 2.5G GPRS SGSN can be upgraded to a wireless access gateway, and the MSC will be upgraded to become 3G capabilities and support new wireless access gateway interfaces. In order to enable voice to be built on a distributed package exchange network, more grouping networks are introduced into the network, including, UMTS communication server CS, universal voice server universal audio Server, PSTN gateway. In order to support the interconnection of 2G / 2.5G access network, the wireless access gateway needs to be upgraded to support A and GB interfaces. At the same time, mobile operators can exchange technology in the existing multi-service core network. Transition to MPLS will provide unprecedented features to the core network, which meets the requirements of mobile high-speed multimedia services at the speed, route, traffic engineering, QoS management, VPN, and scalable capability.
The concept of full IP is divided into two layers: business and network layers. The future business will be unified based on IP. This is no doubt, and in the network level, the concept of full IP is not simply carrying the entire business in existing IP networks, but emphasizing the integration IP technology to build core. network. R00 proposes: The network structure of all IP UMTS should make the core network independently of the underlying transmission mechanism. Nowadays, the industry recognizes that the next generation of core networks will be based on MPLS, MPLS is a core exchange technology for future fusion, which effectively inherits and develops their own advantages of IP and ATM, namely "access IP advantage core ATM advantage" strategy . MPLS changed the connection of the previous routing must "multi-hop" through a large number of routing devices, or must pass through the VC of the ATM, but changed from a standard LSR tag switched route to implement routing, that is, through "label" implementation Exchange, unified use of MPLS to carry various services in the underlying business, make the network level simple, cost reduction, and further improve the management of networks and services, MPLS multi-protocol processing features make it have across multiple media networks, not just ATM 中The ability, can provide a unified control mechanism for large-capacity networks, which makes operators get more flexible scalability, operators can use existing ATM switches, and gradually increase the MPLS function more effectively improve packets. Forwarding capabilities.
With the development of 3G services, the network's demand for bandwidth will expire quickly, and it can take into account the IP / Optical evolution. The existing multi-service platform will seamlessly evolve to Taibit terabit i IP core network, which not only enables operators to be able to economically, flexibly deal with current business traffic, but also meet the future of higher traffic requirements from G bit to T bits, no need to upgrade step by step, no impact on the continuity of the business. Finally, light-exchanged equipment will enter 3G core network, and the overall improvement of the optical network on bandwidth and exchange capacity will release huge energy for the entire 3G rapid development. At this time, the light layer will use the Ason automaticly switch Optical Network standard, the IP layer uses the MPLS standard, and the coordination between the two layers will be implemented by strategy-based network intelligence, such network intelligence can collect information and business requirements from each layer. And control, which will enable operators to build the network with open standard interfaces. In this way, a network-based smart, interface open, a core network based on Tapit-level capacity and optical exchange is present in front of us. Nortel Network has achieved leaders in the core data exchange field and optical communication field, and its core network evolution program is recognized by operators. It has been rated as the clearest, smooth evolution route, has been successfully applied to the world. Multiple 3G contracts have been signed within the scope. This powerful 3G core network will promote the development of a new generation of wireless services, inserting a wings of the mobile Internet.
From the "Telecom World News" 2001.36
